Pneumatic actuator for keyboard operated machine



Jime27,1967 J.C.LAMB|OTTE 7 3,327,827

PNEUMATIC ACTUATOR FOR KEYBOARD OPERATED MACHINE Filed Jan. 24, 1966 JOSEPH C. LAMBlOTTE United States Patent 3,327,827 PNEUMATIC ACTUATOR FOR KEYBOARD OPERATED MACHINE Joseph C. Lambiotte, Lexington, Ky., assignor to International Business Machines Corporation, Armouk, N.Y., a corporation of New York Filed Jan. 24, 1966, Ser. No. 522,613 11 Claims. (Cl. 19719) This pneumatic actuator is particularly characterized by its simple construction, its ease of manufacture and assembly, its high speed of operation, and its relatively high efficiency.

Key operated mechanisms such as typewriters, pianos,

'et'c., are often automated by the provision of individual actuators to operate the several keylevers in response to record data. Wherever a large number of keys are involved, the manufacturing and assembly cost of the individual actuators becomes a significant consideration. Electromechanical actuators, such as solenoids, have been employed but are relatively expensive. Traditionally,

player pianos and automatic typewriters have employed '1iam FJVoit, Jr., have been proposed to provide a novel version of an expansible chamber motor, having a very fast response due to the extremely low mass of the moving tape member.

Inasmuch as pneumatic actuators are ordinarily ancillary to complex mechanical equipment presenting various problems of space, assembly access, operating force, etc., the principal object of my invention has been to provide a pneumatic actuator of ultrasimple construction to maximize the inherent low cost advantages of pneumatic force generation.

Another object of my invention has been to provide a pneumatic actuator that can be readily assembled with a device to be operated, without requiring modification of the operated device.

' A further object of my invention has been to provide a pneumatic actuator having extremely low mass to minimize inertial effects that reduce operating speed.

While the objects of my invention are directed principally to the structure of individual actuators, attention is called to application Serial Number 522,614 Multi Element Pneumatic Actuator, led by John E. Jones, on

January 24, 1966, the objects of which are directed to somewhatsimilar actuators arranged in a compact bank construction for use where space is at a premium.

One phase of my invention relates to the employment of a closed loop of thin flexible tape as the sole moving member in a pneumatic actuator formed by two parallel opposed sidewalls and achamber closure wall or :port, all

of which are stationary.

The closed loop of tape can be formed either as an integral or continuous loop, or can be formed by joining the ends of a strip. Both embodiments permit easy assembly of the moving part with an associated operated part by direct connection therebetween. The closed loop, being. the only moving member, presents a low mas and hence low inertia to the system, thereby permitting fast operation.

A second, more specific phase of my invention involves a particular construction of an actuator wherein the closure wall is provided internally of the loop, either in the form of a spool-like core, or an internal surface, both of which engage inside surfaces of the loop to complete enclosure of the chamber boundary formed by the loop. This embodiment of my invention presents a minimum of friction to the system, as an adequate seal at the closure wall edges is provided simply by the tension in the loop itself. Actuating pressure is introduced into the loop causing an expansion of the chamber formed thereby, and

actuation of a connected operating member. If the actuator is made spool-like in shape, the stroke actuation can be readily limited by the extent of the side flanges.

Another embodiment of my invention employs a shelllike closure wall that engages the outer surfaces of the loop causing inner surfaces of the loop to close upon themselves and form a chamber within the loop. In this embodiment, the stroke is limited by physically limiting the movement of the tape itself. This latter-limiting approach provides a further advantage of permitting controlled deceleration of the stroke as effective area is subtracted from the tape upon contact with the shell wall. The stroke can be limited also by making the actuator shell-like in shape. It has the disadvantage of requiring greater internal friction caused by the forces required to adequately seal the space between the tapes.

All of my actuators have the desirable advantage of permitting significant leakage whereby actuation against a load remains only so long as fluid is being supplied. The leakage thus permits control of the actuators by single acting rather than double acting valve mechanisms.

The foregoing and other objects, features, and advantages of my invention will be apparent to those skilled in the art upon reading the following more specific description of a preferred illustrative embodiment of my invention, wherein reference is made to the accompanying drawings, of which:

FIGURE 1 is a partial perspective view of an actuator constructed in accordance with one mode of my invention as assembled with a typical typewriter keylever of known construction.

FIGURE 2 is a front vertical cross-sectional view of the actuator shown in FIGURE 1 taken along lines IIII thereof;

FIGURE 3 is a front vertical view of an actuator like that shown in FIGURES 1 and 2 illustrating a degree of versatility of my invention; I

FIGURE 4 is a front vertical cross-sectional view of an actuator according to a modified version of my in vention;

FIGURE 5 is a side vertical cross-sectional view of the actuator shown in FIGURE 4 and taken along lines V Vthereof;

FIGURE 6 is a front vertical cross-sectional view of an actuator. according to a further modification of my invention. 1

Referring now more specifically to the drawings, in FIGURES 1 and 2 there is shown a pneumatic actuator 10 including a flexible, closed, preferably continuous loop, strip or tape 11 that is looped over a spring biased operating member, such as a keylever 21 in force transmitting relationship therewith to provide an actuating input thereto. The tape 11 thus [provides its own output connection means; however, other means such as rivets can be employed. The keylever 21 is shown as being similar to that disclosed in US. Patent 2,919,002 Selection Mechanism for a Single Printing Element Typewriter, issued December 29, 1959, to L. E. Palmer and is biased upwardly by a leaf spring 22 to its non-actuated position. The keylever 21 operates to downwardly displace an interposer or other load 23. It will be understood that the keylever shown is illustrative only, and various load bearing members can be actuated by my actuator.

The actuator 10 comprises a pair of parallelsidewalls 12 that are spaced a distance 13 approximately equal to the width of the tape 11 as defined by its substantially parallel side edges 11a. An effective pneumatic seal is thus formed between the tape 11 and sidewalls 12. The sidewalls 12 .are joined and supported in their parallel relationship by a wall forming core or reaction surface 14 about which the tape 11 is looped. The core 14 engages laterally opposed portions of the tape inner surface 11b to complete enclosure to the boundary of an expandable, pressurizeable chamber 15 between opposite sides of the tape loop 11. A pilot chamber or depression 16 is integrally formed in the core 14 along the lower surface thereof in contact with the tape 11 to permit the initial development of a pneumatic pressure across a significant area of the tape.

The actuator is controlled through a signal input conduit or inlet 17 that is connected to deliver fluid received from a source of control data such as selectively operable remote key valve V to the depression 16 and chamber 15. Other inputs, such as a paper tape reader, or transmission line solenoid valve, can be employed.

It will be seen that upon application of fluid pressure to inlet 17, a super ambient pressure will be created within the chamber bounded by the tape 11, the spool 14, and the sidewalls 12. The chamber 15 expands downwardly and pulls the keylever 21 in its actuating direction against leaf spring 22. The length of the actuating stroke can be limited, if desired, by designing the extent of sidewalls 12, such that a portion of the tape 11 will go beyond the sidewalls 12 at the stroke limit point of its travel, creating an exhaust as shown by the broken lines. Upon termination of a pneumatic signal in inlet 17, leakage in the system will quickly dissipate any residual forces and leaf spring 22 will return the actuator to its initial position.

It will be seen that the actuator shown in FIGURES 1 and 2 can be readily assembled by simply slipping the tape loop 11 over the spool-like stationary structure and over the keylever 21 to provide a complete assembled actuating device.

Actuators are often required for apparatus designed principally for non-automated use which lack specific design consideration for actuating parts. The flexible tape 11, as shown in FIGURES 1 and 2, permits a versatile illustration, as illustrated in FIGURE 3, wherein the actuator 10 is located at right angles to its position as shown in FIGURE 1. A simple guide post P directs the flexible tape 11 around a right angle turn and to the keylever 21. It will be appreciated that even a 180 turn could be accomplished if required to position the actuator within a predetermined unalterable space. It will also be seen that that actuator 10 can be constructed to accommodate an available space by varying either the width 18 of the core 14 or the flange spacing distance 13 to achieve the desired force within a given shaped space. It will also be seen that the tape 11 need not be uniform width along its total peripherial extent, but only in the region of sidewalls 12.

By way of example, an actuator 10 constructed in accordance with FIGURES 1 and 2 having dimensions 13 and 18 of A and 1%", respectively, has been employed to trip a conventional spring clutch requiring a stroke between 0.100" and 0.200". The clutch was tripped in between 6 and 10 milliseconds with a developed force of /2 pound produced by a one p.s.i. air source. Its operation was unaffected to temperature variations between room temperature and 200 F.

In FIGURES 4 and 5 a modified actuator is shown. A flexible tape loop 31 similar to tape loop 11 above, engages an internal wall or reaction surface 32 by passing through vented chamber forming shell or wall spaced slots 33, 34, opposed parallel sidewalls 35 and 36, corresponding in function to the sidewalls 12 of FIGURE 1. The tape 31 is operated against an operating member 21 like that shown in FIGURE 1 by pressure introduced through input conduit 37 into the expansible chamber 38 bounded by the tape 31, the opposed sidewalls 35, and reaction surface 32. The stroke is limited and motion decelerated as the tape 31 progressively moves into the shell 34 and comes in contact therewith and shell contacting surface area portions of the tape 31 lose their effective pressure differential.

FIGURE 6 shows an actuator 40 somewhat similar to that shown in FIGURES 4 and 5 in that a vented outer shell or wall 41 that supports parallel side walls (not separately shown) in their spaced relation. The shell provides a stroke limiting and decelerating surface operative like that of FIGURE 4. A loop of flexible tape 42 engages an actuating member 21 as in the previousexamples, but passes through a single slot 43 in the shell 41 to form an expansible chamber 44 bounded by the parallel sidewalls and the tape 42 as enclosed by contact between its inner surfaces. Such contact is effected by the surface edges of the slot 43 which engage laterally opposed portions of the tape outer surface 42a to seal the chamber 44. Air is introduced into the chamber 44 through input conduit 45 causing expansion thereof. Force reaction against the edges of the slot 43 during expansion causes the downward movement of the tape 42 and consequent operation of the member 21.

Those skilled in the art will recognize that I have provided an ultra-simple, yet reliable and versatile pneumatic actuator that is capable of'high speed operation due to its inherent low mass.

While some specific embodiments have been shown for purposes of illustration and compliance with statutory requirements, it will be recognized that various modifications, additions, and deletions can be made without departing from the spirit and scope of my invention. For example, the benefits of my closed loop as to the chamber forming portion of my invention can be achieved independently of the benefits obtainable from the operating connection member portion of the closed loop. Other modifications will be obvious to those skilled in the art, and my invention is to be limited only by the appended claims.

I claim:

1. A pneumatic actuator for moving an operating member against a load and including a pressurizeable chamber having an expansible boundary, and fluid inlet means operatively connected with the chamber, wherein the improvement comprises:

a loop of flexible tape having a surface portion bounded by substantially parallel lateral side edges and defining a portion of the chamber boundary, means for operatively connecting said tape in force transmitting relationship to the operating member,

a pair of parallel side walls embracing said side edges of said loop and defining a further portion of the chamber boundary, and

relatively stationary reaction surface means slidably engaging said surface portion of said loop to enclose the portion of the chamber boundary defined by said loop.

2. A pneumatic actuator as defined in claim 1 wherein said tape loop is closed and continuous and said reaction surface means engages laterally opposed surface portions of said loop.

3. A pneumatic actuator as defined in claim 2 wherein said reaction surface means engages inner surface portions of said loop and directly defines a portion of the chamber boundary.

4. A pneumatic actuator as defined in claim 2 wherein said reaction surface means includes a pair of stationary surface edges defining a slot, said loop passes through said slot, and said surface edges engage opposed outer surface portions of said loop to enclose the portion of the chamber boundary defined by said loop.

5. A pneumatic actuator as defined in claim 2 further including means forming part of said actuator for limiting the expansion of said chamber.

6. A pneumatic actuator as defined in claim 5 wherein said expansion limiting means comprises means carried by said sidewalls defining an exhaust from said chamber.

7. A pneumatic actuator as defined in claim 5 wherein said expansion limit means comprises an outer wall connected between said parallel surfaces and positioned to intercept said loop at a predetermined degree of expansion thereof.

8. In combination with an operating member for moving a load, a pneumatic actuator including a pressurizeable chamber having an expansible boundary wherein the improvement comprises:

a loop of flexible tape having a surface portion bounded by substantially parallel lateral side edges and defining a portion of the chamber boundary, said tape being operatively connected in force transmitting relationship to the operating member,

a pair of parallel side walls embracing said side edges of said loop and defining a further portion of the chamber boundary,

relatively stationary reaction surface means slidably engaging said surface portion of said loop to enclose the portion of the chamber boundary defined by said loop, and

means for selectively creating a fluid pressure within the chamber greater than the pressure outside thereof.

9. Apparatus in combination as defined in claim 8 wherein said tape loop is closed and continuous and said reaction surface means engages laterally opposed surface portions of said loop.

10. Apparatus in combination as defined in claim 9 wherein said reaction surface means engages inner surface portions of said loop and directly defines a portion of the chamber boundary.

11. Apparatus in combination as defined in claim 9 when said reaction surface means includes a pair of stationary surface edges defining a slot, said loop passes through said slot, and said surface edges engage opposed outer surface portions of said loop to enclose the portion of the chamber boundary defined by said loop.

References Cited UNITED STATES PATENTS 848,207 3/1907 Rodesch 84---29 1,003,279 9/1911 MacArthur 8450 1,005,793 10/1911 Atkinson 84-50 1,842,883 1/1932 Swanson 197-19 2,795,668 6/1957 Puckett 200-81 2,991,763 7/1961 Marette 92-89 X WILLIAM B. PENN, Primary Examiner.

ROBERT E. PULFREY, Examiner.

E. S. BURR, Assistant Examiner. 

1. A PNEUMATIC ACTUATOR FOR MOVING AN OPERATING MEMBER AGAINST A LOAD AND INCLUDING A PRESSURIZEABLE CHAMBER HAVING AN EXPANSIBLE BOUNDARY, AND FLUID INLET MEANS OPERATIVELY CONNECTED WITH THE CHAMBER, WHEREIN THE IMPROVEMENT COMPRISES: A LOOP OF FLEXIBLE TAPE HAVING A SURFACE PORTION BOUNDED BY SUBSTANTIALLY PARALLEL LATERAL SIDE EDGES AND DEFINING A PORTION OF THE CHAMBER BOUNDARY, MEANS FOR OPERATIVELY CONNECTING SAID TAPE IN FORCE TRANSMITTING RELATIONSHIP TO THE OPERATING MEMBER, A PAIR OF PARALLEL SIDE WALLS EMBRACING SAID SIDE EDGES OF SAID LOOP AND DEFINING A FURTHER PORTION OF THE CHAMBER BOUNDARY, AND RELATIVELY STATIONARY REACTION SURFACE MEANS SLIDABLY ENGAGING SAID SURFACE PORTION OF SAID LOOP TO ENCLOSE THE PORTION OF THE CHAMBER BOUNDARY DEFINED BY SAID LOOP. 